- Bring sake to a boil in a saucepan over medium heat. Allow to boil for 30 secs.
- Lower heat, then add mirin and Japanese soy sauce, and stir through.
- Add kombu and dried bonito, stir through, then simmer for 5 mins.
- Remove from heat and set aside until completely cooled.
- Strain mixture, then use mentsuyu as a soup base or dipping sauce.